I am interfacing an external WiFi module card supporting SDIO 3.0 with IMX6SLL-EVK host platform. IMX6SLL-EVK host is running Linux kernel 4.9.11 and driver is inserted properly into the kernel. The SDIO port used is uSDHC3.
I am attaching here the dmesg MMC logs during bootup with the WiFI card inserted
The SDIO port sattus information is given below.
ubuntu@arm:~$ sudo cat /sys/kernel/debug/mmc2/ios
clock: 208000000 Hz
actual clock: 198000000 Hz
vdd: 18 (3.0 ~ 3.1 V)
bus mode: 2 (push-pull)
chip select: 0 (don't care)
power mode: 2 (on)
bus width: 2 (4 bits)
timing spec: 6 (sd uhs SDR104)
signal voltage: 1 (1.80 V)
driver type: 0 (driver type B)
I believe that WiFi card is detected in UHS SDR104 mode. But when I test WiFi transmit throughput, It is around 100Mbps only. It is similar to the SDIO 2.0 mode throughput observed in some laptop hosts.
I expect the transmit throughput to be more than atleast 200Mbps.
Is there any limitation in iMX6SLL-EVK performace. pls, let me know the problem in this scenario.
Also suggest some platforms supporting high throughput in SDIO 3.0 mode.
Thanks for the response. I have disabled the MMC_DEBUG which was causing some drop in throughput.
After this change throughput increased more to 170Mbps.
Also one more issue I am observing is that, MMC Timeout waiting for Hardware interrupt. This is observed sometimes when throughput test is running and the SDIO slot becomes unresponsive. WiFi Card has to be reinserted into slot to restart the SDIO slot operation. The error log is below.
ubuntu@arm:~$ mmc2: Timeout waiting for hardware interrupt.
sdhci: =========== REGISTER DUMP (mmc2)===========
sdhci: Sys addr: 0xe4a00240 | Version: 0x00000002
sdhci: Blk size: 0x00000100 | Blk cnt: 0x00000061
sdhci: Argument: 0x9d9f0061 | Trn mode: 0x00000023
sdhci: Present: 0x01f8810e | Host ctl: 0x00000013
sdhci: Power: 0x00000002 | Blk gap: 0x00000080
sdhci: Wake-up: 0x00000008 | Clock: 0x0000001f
sdhci: Timeout: 0x0000008f | Int stat: 0x00000000
sdhci: Int enab: 0x107f110b | Sig enab: 0x107f110b
sdhci: AC12 err: 0x00000000 | Slot int: 0x00000302
sdhci: Caps: 0x07eb0000 | Caps_1: 0x8000b407
sdhci: Cmd: 0x0000353a | Max curr: 0x00ffffff
sdhci: Host ctl2: 0x00000088
sdhci: ADMA Err: 0x00000003 | ADMA Ptr: 0xec4d1204
please try to test some SD 3.0 SDR104 card, not wifi as
wifi card throughput may be affected by other factors for example
environment noise conditions.